Evaluation of Site Amplification for the Seismic Protection of a Strategic District in Naples

Since the 1980s, a Business District is located in the eastern area of Naples. The first pioneer studies carried out in this area showed that a significant variability of site amplification can be predicted due to the morphology of seismic bedrock and to the presence of vanishing lenses of peat. More recently, the seismic vulnerability of the New Law Court was assessed adopting the hypothesis of 1D conditions for the seismic response analysis. This paper aims at verifying the reliability of this assumption, evaluating the 2D seismic site response of a representative geological section. Geotechnical characterization of the soil deposits has been carried out by integrating the available experimental data with literature data. Two suites of accelerograms have been considered as input motions, representative of ‘near field’ and ‘far field’ seismic events. Equivalent linear and non-linear 2D analyses have been carried out through a finite element and a finite difference code, respectively. Results provide insights on the non-linear soil behaviour of peat and allow for recognizing the limits and advantages of both adopted approaches. Finally, the comparison between the results of 2D and 1D analyses allows for highlighting the effects of focalization of seismic waves on the amplification of the ground motion at the surface.